Method of continuously measuring the progress of development of photographic emulsions

ABSTRACT

The progress of the development of a silver halide photographic emulsion is continuously measured by suitably exposing a dilute liquid silver halide photographic emulsion, uniformly mixing the emulsion with a developer, continuously passing the mixture through a flow cell and continuously measuring the absorbance of the reduced silver in the emulsion passing through the cell.

United States Patent [191 [111 3,864,082

Kato Feb. 4, 1975 1 METHOD OF CONTINUOUSLY [56] References Cited MEASURING THE PROGRESS OF UNITED STATES PATENTS DEVELOPMENT OF PHOTOGRAPHIC 2,590,830 3/1952 Williford et a1 96/63 EMULSIONS 3,507,617 4/1970 Kliem 96/63 Inventor: Kate Kanagawa Japan 3,725,071 4/1973 Seelbinder et a1. 96/63 [73] Assignee: Fuji Photo Film Co., Ltd., Minami Primary ExaminerMary F. Kelley Ashigara-shi, Kanagawa, Japan Attorney, Agent, or Firm-Sughrue, Rotwell, Mion, 22 Filed: Feb. 14, 1973 Macpeak [21] Appl. No.: 332,445 [57] ABSTRACT The progress of the development of a silver halide [30] Foreign Application priority Data photographic emulsion is continuously measured by Feb 15 1972 la an 4745772 suitably exposing a dilute liquid silver halide photop graphic emulsion, uniformly mixing the emulsion with [52] U S Cl 23/230 R 96/50 R 96/63 a developer, continuously passing the mixture through [51] G03: 7 Goln 31/06 a flow cell and continuously measuring the absorbance 5s Fieid (ii Search 96/63 50 R 94 R- the reduced Silver in the mulsion passing through 23/230 R, 230 A the 8 Claims, 3 Drawing Figures ABS.

RECORDER PATENTEUFEB 4191s W m T H m L FIG. I

RECORDER HIGH LOW EXPOSURE EXPOSURE UNEXPOSED 552N500 woz zom DEVELOPING TIME FIG 3 1 METHOD OF CONTINUOUSLY MEASURING THE PROGRESS OF DEVELOPMENT OF PHOTOGRAPHIC EMULSIONS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method of dynamically measuring the development of a liquid photographic emulsion, that is to say, a method of continuously measuring the progress of development of a liquid photographic emulsion.

2. Description of the Prior Art A silver halide photographic emulsion is apt to change in photographic properties such as sensitivity, fog, etc. and thus it is difficult to provide the desired photographic properties to the finally produced photographic emulsion.

The simplest known method for obtaining photographic emulsions having definite photographic properties is a sensitometric method. According to this method, a part of a photographic emulsion produced is coated on a support, dried and after exposing, developing, and fixing the photographic emulsion layer, the blackened density of the layer is measured. In the production of photographic emulsions, by conducting some operations based on the values obtained by this measurement, photographic emulsions having desired photographic properties are produced.

However, since the above-mentioned sensitometric method requires the steps of coating and drying a photographic emulsion, and further exposing, developing, and fixing the emulsion layer, it requires a considerable length of time and great skill.

On the other hand, to omit the steps of coating and drying photographic emulsions, a sensitometric method using liquid photographic emulsions has been disclosed in U.S. Pat. Nos. 2,590,830 and 3,507,617.

However, this liquid sen sitometric method basically follows the conventional method of evaluating the photographic properties by using a support such as a film or a glass plate and consequently the method is lacking in speed and isunsuitable as a practical method of determining the photographic properties of photographic emulsions in the continuous production thereof.

An improvement in such a method is described in French Patent No. 2,021,886 and British Patent No. 1,304,799 where the progress of the development of a photographic emulsion is continuously measured, the photographic properties of the emulsion are evaluated from the development progress curve obtained and the results are utilized for the continuous production of the photographic emulsion.

In such a method, to prevent the photographic emulsions from being fogged, light (e.g., near infrared) having a wave length outside the sensitive wave length region of the photographic emulsion is introduced into the mixing tank for the liquid photographic emulsion and a developer, and the progress of development is continuously measured using an optical system. Therefore, this method presents the problems of cost and measurement accuracy from the viewpoint that an optical guide such as an optical fiber must be used to introduce the near infrared rays into the mixing tank or, alternatively, a mixing tank having a complicated structure must be used, and stable and readily available photoelectric elements cannot easily be used.

SUMMARY OF THE INVENTION The object of this invention is, therefore, to provide a method of continuously measuring the progress of the development of a liquid photographic emulsion accurately and quickly without being restricted to special optical means or other special apparatus.

The above object of this invention is attained by using a flow cell for the measurement, that is, when a liquid photographic emulsion is mixed with a developer in a vessel to a definite extent, the emulsion is caused to react with the developer and a development reaction forming reduced silver proceeds, and the mixture is, without adding a fixing solution or a stopping solution, introduced into a flow cell and passed through the fiow cell for the period of time necessary for measurement. In the flow cell, the mixture is irradiated by light to quantitatively measure the amount of reduced silver using an optical means.

The light passed through the front wall of the flow cell, the mixture passing through the cell, and'the back wall of the flow cell is continuously measured and recorded by means of a photometric means, whereby the amount of light absorbed by the reduced silver in the mixture through the flow cell is quantitatively measured.

The mixture is then withdrawn from the end of the flow cell.

Because the method of this invention starts the measurement continuously from the state immediately after mixing the liquid photographic emulsion and the developer, the development reaction of the photographic emulsion, i.e., the formation of reduced silver of the emulsion, is continuously measured with the passage of time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing one embodiment of a flow cell as can be used in the present invention.

FIG. 2 is a schematic view showing an embodiment of the method of this invention, and

FIG. 3 is a development progress curve showing the photographic properties measured by the method of this invention illustrated in the example.

DETAILED DESCRIPTION OF THE INVENTION By the term flow cell in the specification and claims is meant a small cell having portions transparqnt to the light for measuring the absorbance of the mixture in the cell, having a known thickness in the direction of the passage of the light and having two openings for passing therethrough the mixture of photographic emulsion and developer.

The thickness of the flow cell in the passage direction of the measurement light is selected so that the light passed through the cell can be sufficiently measured by the photometric means and when a dilute photographic emulsion is used, the thickness of the flow cell is usually from about 1 mm. to about 10 mm. (distance of light passage through flowing liquid).

The inlet portion and the outlet portion of the flow cell must be so connected to the body of the cell for passing the measurement light that the liquid mixture can pass therethrough smoothly'without forming disturbances and local retention of the liquid mixture, e.g., using a shape as in FIG. 1.

If the above requirements are satisfied, any shapes and any materials can be employed for the flow cell to be used in the method of the invention. The flow cell used in the example is illustrated in FIG. 1 of the accompanying drawings.

As the measurement light in this invention, light of any wave length, such as near ultraviolet, visible, infrared, etc., can be utilized regardless of the sensitivity of the photographic emulsion because even if the photographic emulsion is exposed to the measurement light employed, the liquid mixture of the photographic emulsion and developer flows through the flow cell and is immediately withdrawn from the cell, and thus such an exposure does not have any influence on the measurement.

The invention will now be described by referring to the accompanying drawings.

Referring to FIG. 2, over a mixing tank 12 equipped with a heat jacket 11 and an agitator 16 are disposed a vessel containing a photographic emulsion 13, a vessel containing a developer 14, and a vessel containing a diluent 15. A flow cell 18 as shown in FIG. 1 is connected to the bottom of the mixing tank 12 by a conduit 17 and a light source 19 and a light receptor 21 are disposed at the opposite sides of the flow cell. A filter 20 for selecting the light of a proper wave length is placed between the light source 19 and the flow cell 18.

During the normal practice of the method of this invention a conventional liquid silver halide emulsion 13 is supplied to the tank 12 having the heating jacket 11. A diluent such as water or an aqueous gelatin solution is added to the photographic emulsion 15 in the tank to dilute it to a maximum of 1/1000 of the original concentration and the mixture is sufficiently mixed by means of the agitator 16. Then, if necessary, the mixture in the tank is exposed to a light source (not shown) disposed over the mixing tank for a definite period of time while stirring the mixture uniformly. Exposure conditions used are essentially the same as for a silver halide light-sensitive material.

One would, of course, expose the emulsion when analyzing the exposure specifics, but not in the case that the fog specifics are being analyzed. This is well known in the art of sensitometry.

A developer 14 is supplied to the mixing tank and the resultant mixture is sufficiently mixed by the agitator 16 to start the development. Neither fixing solution nor stopping solution is added to the mixture in the tank.

The mixture 16' is then fed to the flow cell 18 from the bottom of the tank 12 through a conduit 17 and at the same time light having a definite wave length is applied to irradiate the mixture in the cell. The light passed through the flow cell is detected by the light receptor 21, whereby the absorbance of the reduced silver in the photographic emulsion is measured.

The photographic emulsion mixture is then withdrawn from the outlet of the flow cell. After the measurement is finished, the device used for the measurement can be easily cleaned by passing washing water through the flow cell and the conduit connected to the cell.

0 absorbance is usually defined as the .absorbance of distilled water which is put in a cell in case of washing, 100 percent absorbance is defined as the absorbance when the light source is off. I

The time of passage between the mixing tank and flow cell is selected so that the reaction does not overly proceed between the mixing tank and flow cell. When the emulsions tested are diluted, reaction is slow and passage time is not important. Little is gained by having the passage time over 10 seconds, however.

in order that the absorbance of the photographic emulsion blackened in the flow cell is in the measurable range of the absorbance meter (e.g., the measurement is impossible if the emulsion has the concentration of an ordinary photographic emulsion for photographic purpose), it is desirable that the measurement of the absorbance be conducted under the conditions of:

l. diluting the photographic emulsion to 1/10 to 1/1000 of the concentration of an ordinary photographic emulsion in the final state containing the developer.

it is to be understood that the necessity for dilution is imposed by the relatively high solids concentration of an ordinary, conventional photographic emulsion. While the method of the present invention can be used with non-diluted special application emulsions, for

practically encountered industrial applications dilution will be necessary to permit the use of standard photomultipliers, etc.

Dilution is, of course, only necessary to the point of sufficient light passage, though greater dilution can, and will often, be used. Usually dilution is with an aqueous gelatin solution since sometimes silver halide will separate from a binder if only water is used. Taking care so as to not overdilute, water per se can, of course, be used, but the extra care needed is generally not nec-' essary in view of the availability of aqueous gelatin in the photographic manufacturing industry.

2. selecting the thickness of the flow cell to be about 1 to about 10 mm.

3. restricting, the absorbance (density) of the photographic emulsion to be in the range of about 0 to about 4 in which an ordinary absorbance meter (densitometer) can be used.

In addition, there is no particular limitation on the amount of measurement light irradiated since the amount of light can be controlled by the sensitivity of the photometric device employed (for example, by employing a conventional photomultiplier, semiconductor element, etc., e.g., it is possible to use an 5-1 photomultiplier containing a cathode made of Cs Sb, Sl0 photomultiplier containing a cathode made of Bi- Ag-OCs, etc.).

The speed of the emulsion mixture passing through the flow cell may be such that the photographic emulsion exposed by the measurement light is withdrawn from the flow cell before the emulsion is blackened by the development, and although it depends upon the sensitivity of the photographic emulsion, the speed is generally higher than 20 cm/min (line velocity).

On the other hand, the maximum flow rate of the mixture passing through the flow meter depends upon the capacity of the mixing tank and the development time. For example, if the maximum capacity of the tank is 10 liters and the maximum development period is 5 minutes, in such a case the maximum flow rate is about 2,000 cc/min.

Thus, in the method of this invention the mixture 16 is passed through the flow cell 18, and since the liquid photographic emulsion 13 is uniformly mixed with the developer 14 the development of the photographic emulsion proceeding in the tank 12 is dynamically measured, that is to say, the method of this invention is equivalent to the procedure of continuously sampling the photographic emulsion under development with the passage of time and measuring the formation and growing steps of the reduced silver.

The kinds of emulsions analyzed in accordance with this invention are not limited. For instance, there are silver halides such as silver chloride, silver bromide, silver chlorobromide, silver iodobromide, silver chlorobromide, silver bromide salts, silver iodobromide salts, generally in combination with natural poly-materials such as gelatin, synthesized poly-materials such as polyvinyl alcohol or a mixture thereof, as a protective colloid.

The emulsion is diluted, if necessary, to -1000 times by a developer, water or gelatin, most often a -100 fold dilution being sufficient.

The mixture ratio of the emulsion with a developing solution is the same as developing the emulsion coated on the film.

Therefore, as the uses of the film differ depending on the emulsion, this ratio also differs with the kind of emulsion.

According to the method of this invention, the following advantages are obtained.

1. Since light of a wave length in the sensitive wave length region of the photographic emulsion to be measured can be employed as the measurement light, the method of this invention can be applied to any photographic emulsions having any sensitive wave length region, and further there are no restrictions on the apparatus used as is the case of the prior art methods employing near infrared rays. Accordingly, the accuracy of the measurement can be increased and also the method can be practiced at low cost.

2. The apparatus can be easily cleaned after measurement.

The invention will be further clearly explained by the following example.

EXAMPLE A liquid gelatino-silver iodobromide emulsion [Agl 1.02 mol percent, AgNO 121.2 g/Kg, Gelatin 115.1 g/Kg, Br equivalent to Ag in AgNO was diluted in the mixing tank 12 to 1/100 of its original-concentration and was exposed to a light source disposed over the tank 12. A PQ developer (Rendol) was added to the tank in the same weight as the diluted silver halide emulsion and the mixture was stirred while maintaining the temperature of the system at C without adding a fixing solution or a stopping solution. *aqueous solution used) The mixture was then continuously introduced into the flow cell from the bottom of the tank (5 seconds from tank to flow cell) through a pipe utilizing the difference in height between the level of the mixture in the tank and the position of the flow cell. The inside diameter of the pipe was 3 mm and the thickness of the flow cell in the direction of light pass was 5 mm (flow cell dimensions: 5 mm X 8 mm; length 3 cm). The rate of passage through the flow cell was 10 cm/sec. A flow cell as shown in FIG. 1 was used.

Monochromatic light having a wave length of 600 muobtained from a tungsten lamp using an interference filter was passed through the flow cell through which the mixture of the photographic emulsion and t the developer continuously passed and the light passed through the flow cell was continuously measured by means of a photomultiplier S-1 photomultiplier containing a cathode made of Ag-O--Cs).

The development progress curves obtained from a series of photographic emulsions subjected to different amounts of exposure are shown in H6. 3.

The horizontal axis is developing time, and the vertical axis is absorbance coefficient. In the case of 1.0, the absorbance is percent. In the case of 0.0, the absorbance is 0 percent.

When absorbance is defined as A, the absorbance coeffcient is log 10 (A/100)31 1.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

1. A method of continuously measuring the progress of development of a silver halide photographic emulsion which comprises mixing a liquid silner hodide photographic emulsion anda developer, continuously passing the mixture through a flow cell without adding thereto a fixing solution or a stopping solution, irradiating the mixture passing through the flow cell with measurement light having any desired wave length measuring the absorbance of the photographic emulsion, and immediately withdrawing the mixture from the flow cell.

2. The method as set forth in claim 1 wherein said photographic emulsion is exposed to light prior to being introduced into the flow cell.

3. The method as set forth in claim 1 wherein said photographic emulsion is diluted with water or an aqueous gelatin solution before mixing with the developer.

4. The method as set forth in claim 3 wherein said photographic emulsion is diluted to about 1/10 to 1/1000 of its original concentration.

5. The method as set forth in claim 3 wherein said dilution is with an aqueous gelatin solution.

6. The method as set forth in claim 1 wherein the measurement light passes through a sample about 1 mm to about 10 mm thick.

7. The method as set forth in claim 6 where the absorbance of the photographic emulsion is in the range of about 0 to about 4.

8. The method as set forth in claim 6 where the silver halide emulsion comprises gelatin. 

1. A METHOD OF CONTINUOUSLY MEASURING THE PROGRESS OF DEVELOPMENT OF A SILVER HALIDE PHOTOGRAPHIC EMULSION WHICH COMPRISES MIXING A LIQUID SILNER HOLIDE PHOTOGRAPHIC EMULSION AND A DEVELOPER, CONTINUOUSLY PASSING THE MIXTURE THROUGH A FLOW CELL WITHOUT ADDING THERETO A FIXING SOLUTION OR A STOPPING SOLUTION, IRRADIATING THE MIXTURE PASSING THROUGH THE FLOW CELL WITH MEASUREMENT LIGHT HAVING ANY DESIRED WAVE LENGTH MEASURING THE ABSORBANCE OF THE PHOTOGRAPHIC EMULSION, AND IMMEDIATELY WITHDRAWING THE MIXTURE FROM THE FLOW CELL.
 2. THE METHOD AS SET FORTH IN CLAIM 1 WHEREIN SAID PHOTOGRAPHIC EMULSION IS EXPOSED TO LIGHT PRIOR TO LIGHT BEING INTRODUCED INTO THE FLOW CELL.
 3. The method as set forth in claim 1 wherein said photographic emulsion is diluted with water or an aqueous gelatin solution before mixing with the developer.
 4. The method as set forth in claim 3 wherein said photographic emulsion is diluted to about 1/10 to 1/1000 of its original concentration.
 5. The method as set forth in claim 3 wherein said dilution is with an aqueous gelatin solution.
 6. The method as set forth in claim 1 wherein the measurement light passes through a sample about 1 mm to about 10 mm thick.
 7. The method as set forth in claim 6 where the absorbance of the photographic emulsion is in the range of about 0 to about
 4. 8. The method as set forth in claim 6 where the silver halide emulsion comprises gelatin. 